Third Trimester Screening Singapore: Is It Worth the Scan?

Feeling anxious or unsure when your baby will arrive? You are not alone, such uncertainties often spark anxiety and can feel overwhelming in your final weeks. Third-trimester screening tests offer vital insights into your baby’s growth, position, and health, helping you gain control and peace of mind as you approach delivery.

To help you understand this prenatal testing better, let's explore what you can expect from these scans, their pros and cons, and how they can help you prepare with confidence.

What is third-trimester screening?

By the time you reach the third trimester, which is around 28 to 40 weeks, your pregnancy enters its final stage. This period is crucial for closely monitoring your baby’s growth, position, and overall well-being, as well as your health.

Third-trimester screening involves a series of tests and assessments designed to detect any potential issues early. These include checking the baby’s size and position, assessing the placenta and amniotic fluid levels, and identifying risks such as preeclampsia, restricted foetal growth, or preterm (premature) labour.

While not all women require routine scans at this stage, those with higher risk factors may benefit from closer monitoring to help plan for a safe delivery. Understanding what these screenings involve can give you peace of mind in preparing for your baby’s arrival.

What tests are recommended to be performed?

In the third trimester, your doctor may suggest specific tests tailored to your pregnancy’s progress and individual risk factors. These tests help to closely observe aspects that standard check-ups might not fully capture, providing valuable information to guide the final stages of care. The following sections discuss the main tests commonly recommended, explaining their purpose and what you can expect.

Transabdominal and Doppler ultrasound

A transabdominal ultrasound scan involves the use of an ultrasound probe on your stomach to create images of your baby. This helps your doctor assess your baby’s growth, position, placenta location, and amniotic fluid levels.

A Doppler ultrasound is often performed along with the transabdominal ultrasound and is used specifically to measure blood flow in the umbilical cord and placenta to check that your baby is receiving sufficient oxygen and nutrients.

Cardiotocograph (CTG)

Cardiotocography (CTG), also called a non-stress test, is a non-invasive monitoring method that tracks your baby’s heart rate and your uterine contractions. It shows how your baby’s heart responds to movements and can detect signs of distress or reduced oxygen supply. The test involves placing two sensors on your stomach - one to monitor the heartbeat and another to track contractions – usually over 20 minutes.

Group B Streptococcus (GBS) test

The group B strep test is a simple swab taken from the vagina and rectum, usually between weeks 35 and 37 of pregnancy. It detects the presence of GBS bacteria, which some women carry without symptoms but can pass on to their baby during birth.

If you test positive, you will be given antibiotics during labour to reduce the risk of your baby developing an infection. This test is painless and an important step in protecting your baby’s health at delivery.

Want to learn more about which test is needed for your personal circumstance? Schedule an appointment with Thomson Women's Clinic today. Our obstetrics and gynaecology (O&G) specialists can provide personalised guidance for your pregnancy journey.

When is this prenatal screening performed during pregnancy?

Third-trimester screening is generally scheduled between 28 and 36 weeks of pregnancy, depending on your individual health needs and pregnancy progress. During this stage, regular monitoring helps to ensure that your baby is growing well and that any potential concerns can be addressed promptly.

• Women with higher risk factors, such as gestational diabetes, high blood pressure, or complications in previous pregnancies, may require more frequent ultrasounds and tests.

• Additional monitoring allows your care team to better plan for delivery and reduce risks associated with late pregnancy complications.

• Timing may also vary based on clinical symptoms or findings during antenatal appointments.

Your baby’s growth during this stage

Knowing what to expect during your third trimester could help with your anxiety and ease your mental load. Here are some milestones to expect:

• By the third trimester, your baby’s organs are developed and maturing.

• Rapid weight gain occurs – about half a pound per week.

• Your baby's movements become stronger and more noticeable.

• Positioning becomes important; most babies move into a head-down position before birth.

What to prepare for this screening?

Undergoing a screening close to your due date might seem overwhelming. However, there's no need to worry, as there isn't much preparation required. Here are some practical tips and tricks to help you stay relaxed and ensure the tests proceed smoothly.

• Wear comfortable clothing for easy abdominal access

• Keep a list of symptoms, questions and any unusual changes to share with your doctor

• Drink enough water before the ultrasound unless instructed otherwise

• For GBS testing, no special preparation is usually needed

During the screening

Knowing what to expect for each test can help you mentally prepare for your screening session. Below is what to expect for each test:

• Ultrasound:

  • A warm gel is applied to your lower abdomen, just above your pubic bone. The technician then gently moves a flat probe over your belly to capture images of your baby, placenta, and amniotic fluid.

• Doppler scan:

  • The probe is placed on the side of your lower abdomen, targeting a free-floating section of the umbilical cord. This allows measurement of blood flow to ensure your baby is getting enough oxygen and nutrients.

• CTG:

  • Two elastic belts with sensors are gently wrapped around your abdomen – one to monitor your baby’s heart rate, the other to track contractions. The test usually takes 20-30 minutes and is painless.

• GBS test:

  • A healthcare professional will take a quick swab from your vaginal and rectal areas using a soft cotton swab. This simple test checks for bacteria that could be passed to your baby during birth, helping plan timely treatment.

What do the results mean?

After your prenatal visit, it typically takes a few days for the results to be processed. Your doctor will then review your specific results with you in detail, helping you understand what they mean for your pregnancy. Generally, normal results indicate healthy growth, good blood flow, regular heart rate patterns, and no signs of infection. If any abnormalities are found, further tests or closer monitoring may be recommended to ensure the best care for you and your baby.

Are there any risks for this procedure?

The prenatal tests used in the third trimester (ultrasound, Doppler, and CTG) are non-invasive and considered safe for both mother and baby. No radiation is involved in these tests, removing concerns related to exposure. The Group B Streptococcus swab may cause mild discomfort, but it is not harmful. Overall, these procedures carry minimal to no risk and are performed to ensure your baby’s health and wellbeing.

FAQ

What tests and screenings are done in the third trimester?

The most common tests conducted in the third trimester include the growth ultrasound, Doppler scan, Cardiotocography (CTG) and Group B Streptococcus (GBS) test.

When should I schedule my third trimester scans and check-ups?

It is generally recommended to schedule your third trimester scans and check-ups between 28 and 36 weeks of pregnancy. However, if you have a high pregnancy risk, such as those involving gestational diabetes, hypertension, or multiple births, more frequent visits may be necessary. Your care team will help to guide you on the appropriate schedule based on your individual needs to ensure the health and safety of both you and your baby.

Are there activities I should avoid in the third trimester?

Are there specific positions I should avoid in late pregnancy?

Avoid lying flat on your back for extended periods during late pregnancy, as this position can reduce blood flow to the baby. To ensure optimal blood flow and comfort, it is recommended to sleep on your side, preferably the left side, as it allows for better circulation and support.

What are the signs of a healthy pregnancy in the third trimester?

Can the way I sit affect my baby’s health?

Prolonged slouching may lead to discomfort or back pain, but it will not pose any harm to the baby. Maintaining an upright posture while sitting can aid in promoting an optimal position for the baby, potentially making labour and delivery smoother. By sitting correctly, you provide your body with the necessary support, which can also alleviate tension and pressure on your back during the later stages of pregnancy.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.